When the original Goldion Hammer was destroyed by Repli-Star GaoGaiGar, the Marg Hand survived and was kept in storage aboard the orbit base. During the events of Gaogaigar vs. Betterman, a more advanced hammer was developed as a replacement. Originally, this hammer was only equipped with a simple AI named DoubleMarg. After GoldyMarg was purified from Triple Zero, his Super-AI was installed instead.
True to its name, the Goldion Double Hammer possesses the functionalities of not only the original Goldion Hammer, but the Goldion Motor as well. The gravity shockwave generators are located in a pair of orbs (the Goldion Clackers) that can detach from the ends of the hammers and be controlled via a Plamsa Hold. Although weaker than the original hammer, they can be used repeatedly and with greater precision. Meanwhile, the two hammerheads each contain a miniaturized Goldion Motor, capable of neutralizing gravity shockwaves created by another source. These two abilities can be used together as the Goldion Slicer to create precise planar gravity "blades." This allows the wielder to make targeted cuts against their opponent, (e.g. cutting an enemy's arm off at the elbow) without destroying them entirely.
- The design of the Double Hammer changes between its first and subsequent appearances. In its first appearance in the web novel, it's described as a single hammer with a pair of spheres on the faces of the hammer. One sphere is named Pollux, which generates gravity shockwaves; the other is named Castor, which neutralizes them. When used together, the configuration is called Mode Gemini.
- The print version of the novel was retconned to be consistent with later depictions of the Double Hammer.
- Pollux and Castor's names are derived from the two brightest stars in the constellation Gemini, and by extension, the corresponding figures from Greek mythology.
- Pollux and Castor resembles a Kendama.
- When Goldy is installed in the Double Hammer, he insists on being called GoldyDoubleMarg.